It never ceases to amaze me why on earth so many folks rely on open climb/Descent (Airbus) FLC/Vnav ( Boeing ) and are actually trained to do so for minor vertical profiling.
Most specifically in Airbus chasing a exact speed all over the sky, watching V/S go from 600' to 2600' per min and back again, engines spooling up and down.
Fly the wing pitch and power... simple.